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A205424
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Number of (n+1) X 2 0..3 arrays with the number of equal 2 X 2 subblock diagonal pairs and equal antidiagonal pairs differing from each horizontal or vertical neighbor, and new values 0..3 introduced in row major order.
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2
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15, 102, 870, 7566, 68342, 609086, 5514982, 49362414, 446198614, 4001326366, 36118081094, 324279012558, 2924285830070, 26275991783678, 236797822738342, 2128866218464686, 19176856665755158, 172465933376949982
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = a(n-1) + 73*a(n-2) + 39*a(n-3) - 384*a(n-4) - 432*a(n-5) for n>6.
Empirical g.f.: x*(15 + 87*x - 327*x^2 - 1335*x^3 - 952*x^4 + 144*x^5) / ((1 - 9*x)*(1 - x - 4*x^2)*(1 + 9*x + 12*x^2)). - Colin Barker, Mar 03 2018
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EXAMPLE
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Some solutions for n=4:
0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 1
0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 1
0 1 2 1 0 1 0 0 1 1 0 1 0 1 0 1 2 1 0 0
0 1 0 2 1 0 1 1 1 1 2 1 2 3 1 0 1 2 0 0
1 2 3 1 1 0 2 1 2 1 1 0 3 0 2 0 0 3 1 1
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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